Universidad de Valladolid

Universidad de Valladolid

Defects in semiconductors

The presence of structural defects in crystalline semiconductors often leads to shallow or deep levels in the gap and may also act as additional scattering centers. This often has adverse effects on the performance of devices and the efficiency of solar cells. In addition, semiconductor radiation detectors and devices exposed to radiation may undergo the phenomenon of type inversion, attributed to charge trapping in damage structures. But damage may also have beneficial applications as some defect clusters may be optically active bestowing enhanced optical performance on silicon. The understanding of defect effects is key for defining defect engineering strategies. Because of the large variety of defects that often coexist, experimental structural and spectroscopic characterization techniques find it difficult to assign a given signal to a specific defect.

We use modeling techniques to obtain understanding of structural, energetic, electrical and optical properties of defects and thus assist experimentalists to interpret their results. Simulations are also applied to model the generation mechanisms of ion beam induced defects and its evolution upon annealing.


Structural characterization
Evaluation of the atomic structure of relevant defects and complexes
Energetic characterization
Modeling of the relevant energies that govern the stability and diffusion of defects
Electronic properties
Calculation of the electronic levels of defects to correlate with their macroscopic effects
Dynamical studies
Simulation of dynamics of defects based on fundamental properties